Eternal life of entropy in non-Hermitian quantum systems

摘要

We find a different effect for the behavior of von Neumann entropy. For this we derive the framework for describing von Neumann entropy in non-Hermitian quantum systems and then apply it to a simple interacting PT -symmetric bosonic system. We show that our model is well defined even in the PT -broken regime with the introduction of a time-dependent metric and that it displays three distinct behaviors relating to the PT symmetry of the original time-independent Hamiltonian.When the symmetry is unbroken, the entropy undergoes rapid decay to zero (so-called "sudden death") with a subsequent revival. At the exceptional point it decays asymptotically to zero and when the symmetry is spontaneously broken it decays asymptotically to a finite constant value ("eternal life").